The overall objective of the project is to learn more about the organization and function of chromosomes from higher organisms, particularly at the molecular level. A major effort is directed toward the characterization of the ribosomal DNA in several primitive eukaryotes, particularly Tetrahymena, Paramecium and Physarum. We are examining the molecular morphology of the rDNA by electron microscopy, restriction enzyme digestion, and buoyant density gradient analysis. We are also studying the transcription of RNA in the lateral loops of the giant lampbrush chromosomes from the newt, Triturus. These studies involve in situ nucleic acid hybridization and autoradiography. BIBLIOGRAPHIC REFERENCES: Gall, J.G., Karrer, K. and Yao, M.-C. The Ribosomal DNA of Tetrahymena. In Symposium on the Molecular Biology of the Mammalian Genetic Apparatus (held in Dec. 1975 at Cal. Tech.). In press, 1976. Karrer, K. and Gall, J.G. The Macronuclear Ribosomal DNA of Tetrahymena pyriformis is a Palindrome. J. Mol. Biol., in press, l976.